IC-NRLF
U F
Mechanical Maneuvers
PREPARED BY
THE DEPARTMENT OF ARTILLERY,
COAST ARTILLERY SCHOOL
PUBLISHED BY
THE COAST ARTILLERY JOURNAL
PRINTING PLANT, COAST ARTILLERY SCHOOI
FORT MONROE, VIRGINIA
AUGUST, 1922
1C. A. SCHOOL. 8-14-22-5000.
Mechanical Maneuvers
Mechanical maneuvers are the application of machines and
of mechanical power for mounting, dismounting, moving, and
transporting artillery.
It is of the, utmost importance that officers and enlisted men
designated to execute work of this nature have a knowledge of :
1. The machines, appliances and tools required.
2. How to improvise material.
3. The breaking strength and safe load of the material used.
4. How to obtain the greatest advantage from the power ap-
plied.
5. The safest and speediest method to be used.
The machines and appliances usually employed for moving
heavy artillery are :
Rope, blocks and tackle Sling carts
Handspikes (Levers) Tractors
Hydraulic Jacks E. R. Trucks
Gins Push carts
Shears Mauls
Derricks Sledge Hammer
Blocks, skids, wayplanks and Hatchet
Rollers Axe
Collars Hand saw
Chocks Crosscut saw
Cradles Nails
Capstans, crab or drum
There is a wrong way and a right way to do everything.
There is no condition when the wrong way is more fraught with
the possibilities of disaster than in the handling of heavy weights
or vehicles with improvised tackle. There may be a time when
the tackle that jams or the knot that refuses to be freed, may be
as dangerous to life or equipment as the tackle that breaks or
the hitch that slips. It is very easy to master the simple nomen-
clature of the rigger, and it is equally simple to learn the few
knots, splices, hitches, and riggings necessary to meet any situation
that may arise in the Coast Defenses or in the field.
(i)
2 MECHANICAL MANEUVERS
CORDAGE
A Yarn is a thread formed by twisting several fibres together,
hemp or other fibrous material. The common fibres are: Manila,
Hemp, Jute, and Sisal. Manila fibre is best for ordinary use and
rope made of it should always be used if possible. Hemp is
stronger but not so flexible and deteriorates more rapidly from
moisture.
A Strand is a number of these yarns twisted or spun to-
gether ; three or four strands form a rope if, after they are twisted
together, they measure at least one inch or more in circumference.
Wire Rope contains a number of wires twisted into strands,
three or six of which are laid up around a wire or hemp core. Wire
rope is abiut six times as strong as hemp rope but lacks elasticity
and is difficult to handle. Inasmuch as it is used principally for
permanent rigging and not adapted for field work, it will not be
further considered here.
Ropes are ordinarily composed of three strands laid up right
handed, so that when a strand is followed away from the observer
the rotation will be clock-wise, or laid up with the sun. This
is known as Hawser-Laid, Plain Laid, or Right Handed Rope.
Hawser is also a term applied to larger rope.
Shroud Laid Rope contains four strands usually laid right
handed around a smaller rope called a Heart or Core.
Spun Yarn is made by twisting together, very loosely, two or
more well tarred Yarns, and is also designated by numbers of
yarns, as two yarn, three yarn, etc. It is used for Serving, Seizing.
Stops, Mousing, etc.
Marline is also made of tarred yarn, but it is tightly twisted
and much harder and smoother than spun-yarn. It is not fit for
serving, when the rope served is to be bent up, as it is not pliable
enough to cover the rope in s,uch cases.
The Jaws of a rope are the spaces between the strands. A rope
is Long Jawed or Short Jawed as it is loosely or tightty laid up.
The Lay of a rope is the direction of twist of the strand of the
rope, it is opposite to the twist of yarns in the strands. This
causes the rope to lay together when put under a strain, and the
Yarns and Strands to bind together against each other in all
directions.
The Standing Part is the principal portion or longest part of
the rope.
The End is the free end used in forming a knot or hitch.
MECHANICAL MANEUVERS O
The Bight of a rope is any part not an end. For example a
Bight is a loop formed by binding or doubling the rope.
To Whip a rope is to bind its end with a bit of yarn or twine
to prevent its unraveling.
A rope is Seized when two parts of it are bound together by
spun yarn, marline or cord. Round Seizing is when the seizing
material is wound round both ropes without passing between them,
while in Racking Seizing the seizing material is wound round the
rope in figures of eight.
Pointing is the operation of tapering the end of a rope so that
it will enter a hole or block more easily.
F rapping is several turns about two or more ropes to bind them,
as about lashing, or to draw two ropes and hold them while taking
in slack.
Lashing is the binding or making fast of one object to another
by means of ropes.
A Strap or Sling is usually made of rope, the ends of which
are either spliced or tied together; it is passed round the object
to be moved, the hook of the tackle being passed through both
bights, or through one bight after it has been passed through the
other one.
Mousing a hook is to place seizing about the point and back of
the hook to strengthen it, and to prevent it from disengaging itself.
Worming a rope is filling up the jaws by passing spun yarn
along them, to render the surface smooth for parceling and serving.
Parceling a rope is wrapping narrow strips of canvas about it,
well tarred in order to secure it from being injured by water. The
parceling, is put on with the lay of the rope. Its use is to prevent
chafing or cutting of a rope when a strain is brought against a
rough surface or sharp edge. For this purpose old rope or canvas
wound around is sufficient.
Serving is the laying on of spun yarn or other small material
in turns round the rope, close together, and hove taut by use of a
serving board for small rope and serving mallet for large rope.
Small ropes are sometimes served without being wormed, as the
crevices between the strands are not large enough to make the
surface very uneven; but a large rope is always wormed and par-
celed, before being served. The service is put on against the lay of
the rope.
Cable-Laid rope is composed of nine (9) strands, and is made
by first laying up three ropes of three strands each, with the sun,
and then laying the three ropes up together into one, against
the sun.
4 MECHANICAL MANEUVERS
Right -Hand rope must be coiled with the sun, and Cable-Laid
rope against the sun.
The fibers of Hemp rope are obtained from the Hemp Plant,
those of Manila Rope from a species of Plantain. Hemp Rope is
about one-third stronger than Manila.
The size of rope is always given in inches and fractions, anl is
measured, on the circumference, for the reason that it is seldom
possible to get a squarely cut end in order to measure the diameter.
In making requisitions for rope, it should be clearly indicated that
this measure is the one considered.
Preservation in Store. Ropes should be placed in the upper
stories of buildings, coiled up and labeled; large ropes on skids,
allowing free circulation of air; small ropes hung up to the joists
on pins or hooks. Ropes should not be coiled until perfectly dry;
they should be uncoiled every year, and stretched out for several
days in the dry season. Ropes long in store lose their strength.
A safe general rule for calculating, roughly the strength of all
ropes is as follows: one fourth the square of the circumference
gives the breaking weight in tons of 2000 pounds. Due allowance
must be made for loss of strength by wear and tear.
When using tackles, multiply the weight thus found by one-
half the number of sheaves in the blocks.
Old rope should be carefully examined before attempting to
work with it. A few months exposure weakens a rope 20 to 50
per cent. Dry rot will sometimes make a rope almost useless
without changing its external appearance to any extent. Rope
will sometimes chafe to powder in the center, due to friction be-
tween the strands and yarns while being bent 'Over the sheaves
of blocks. A rope is slightly weakened by tarring and wetting.
Dry ropes shorten quite perceptibly upon being wet and for this
reason it is never safe to leave a tension on rigging when it is
liable to be wet, if an increase on that tension will cause damage.
Rope should always be stopped up, either with the ends or
with the rope-yarn stops, to prevent it getting into a snarl. When
using ropes for hauling, they should never be dragged upon the
ground.
To stop up a coil of rope with the end. Lay off two or three
turns of the coil and take a clove hitch around all parts of one
side of the coil. Do the same on the other side. If the rope
should be rove in ;i l;i<-klc, run it "two blocks" and make a hitch
around the fall between the blocks.
MECHANICAL MANEUVERS 5
KNOTS AND SPLICES
The principle of the knot is that no two parts which would
move in the same direction, if the knot were to slip, should lie
along side or touching one another.
The Square Knot and Thief Knot are excellent illustrations of
this principle.
Square Knot. Take an over-hand knot around a spar; take an
end in each hand and cross them on the same side of the standing
part on which they come up, pass one end around the other, and
bring it up through the bight. This is sometimes called a Reef
Knot. If the ends are crossed the wrong way, sailors call it a
Granny Knot. If the ends come out on opposite sides it is a
Thief Knot.
Single Becket or Sheet Bend (Weaver's Knot). Pass the end
of a rope up thru the bight of another, round both parts of the
other, and under its own part. This does not jam and is useful
in tying two ropes together.
Double Becket. Same as single becket except two turns are
taken round both parts before passing under its own part. Used
to tie ropes of different sizes together. The bight should be taken
in the larger ropes.
Two Half Hitches. Pass the end of the rope around the stand-
ing part and bring it up thru the Bight. This is a half hitch.
Take it around again in the same manner for two half hitches.
Round Turn and Two Half Hitches. Take a round turn
around a stake or post, and secure the end by two half hitches
around the standing part. This is very useful in securing guys to
the stakes.
Fisherman's Bend (Anchor Knot). Take two turns around
the spar with the end of the rope; hitch the end around the
standing part and thru both turns, and then pass the end over
the second and under the first turn. This knot will not jam
when wet.
A Timber Hitch. Take the end of a rope around the spar,
lead it under and over the standing part, and pass two or more
turns around its own part ; pass the first turn over the end part
instead of thru the bight, as in the half hitch. Used in temporarily
securing the ends of ropes to spars.
A Clove Hitch is made by passing the end of a rope round a
spar, over, and bringing it under and round behind its standing
part, over the spar again and up thru its own part. It may then,
b MECHANICAL MANEUVERS
if necessary, be stopped or hitched to its own part, the only dif-
ference between two half hitches and a clove hitch being that
one is hitched round its own standing part and the other is hitched
round a spar or another rope.
A Rolling Hitch. Pass the end of a rope round a spar; take
it round the second time, nearer to the standing part; then carry
it across the standing part, over and round the spar and up thru,
the bight. A strap or tail block is fastened to a rope by this hitch.
Used in shifting the fall from one end of the windlass to the other.
(See Nipper and screw).
A Blackwall Hitch. Form a bight by putting the end of a
rope across and under the standing part; put the hook of a tackle
thru it, the center of the bight resting against the back of the
hook, and the end jammed in the bight of the hook by the standing
part of the rope.
A Cat's Paw. Make a large, bight in a rope, and spread it
open, putting one hand at one part of the bight and the other
at the other, and letting the standing part and end come together,
turn the bight over from you three times, and a small bight will be
formed in each hand, bring the two small bights together, and
put the hook of the tackle thru them both. This is very useful in
applying a purchase or tackle to the fall of another.
A Sheep Shank. Make two long bights in a rope which shall
overlay one another, take a half hitch over the end of each bight
with the standing part which is next to it. Used to shorten rope,
or cut out a weak part, temporarily.
A Bowline Knot. Take the end of a rope in your right hand
and the standing part in your left ; lay the end over the standing
part, and with the left hand make a bight of the standing part
over it; take the end under the lower standing part up over the
cross, and down thru the bight. This is very useful in forming
a temporary eye at the end of a rope.
Bowline on a Bight. The first part is made like the above
bowline, with the double part of a rope, then the bight is pulled
thru sufficiently to allow it to be bent past and come up in the
position shown. It makes a comfortable sling for a man, more so
than a single bight, as the bights may be adjusted to an equal
length.
Running Bowline. This is simply a bowline with a bight
enclosing the standing part.
A Marlinespike Hitch. Lay the marlinespike upon the seizing
stuff, and bring the end over the standing part so as to form a
bight, lay this bight back over the standing part, putting the
MECHANICAL MANEUVERS 7
marlinspike down thru the bight, under the standing part, and up
thru the bight again. Very useful in putting on lashings, etc.
Carrick Bend. Form a bight on a rope and lay the end across
the standing part; stick the bight of another rope up thru the
loop thus formed, and carry the end of the first rope, under the
standing part, and thru the loop formed by its bight, stop each
end to its own standing part.
Splicing is putting the end of ropes together by opening the
strands and placing them into one another, or by putting the
strands of the end of a rope between those of the bight.
A Short Splice. Unlay the strands for a convenient length,
then take an end in each hand, place them one within the other
and draw them close. Hold the end of one rope and three strands
which came from the opposite rope fast in the left hand, or if the
rope .be large, stop them down to it with a rope-yarn. Take the
middle strand, which is free, pass it over the strand which is
first next to it, then thru under the second and out between
the second and third from it, then haul it taut. Pass each of the
six strands in the same manner; first, those of one end and then
those of the other. The same operation may be repeated with each
strand, passing each over the third strand from it, and under the
fourth, and thru, or, as is more usual, after the ends have been
stuck once, untwist each strand, divide the yarns, pass one-half
as above described, and cut off the other half. This tapers the
splice.
A Long Splice. Unlay the ends of two ropes to a distance
three or four times greater than for a short splice, and place them
within one another as for a short splice. Unlay one strand for a
considerable distance and fill up the interval which it leaves with
the opposite strand from the other rope. Twist the ends of these
two together, then do the same with two more strands. The two
remaining strands are twisted together in the place where they
were first crossed. Open the two last named strands, divide in two,
take an overhand knot with the opposite halves, and lead the ends
over the next strand and thru the second as the whole strands
were passed for the short splice. Cut off the other two halves. Do
the same with the others that are placed together, dividing, knot-
ting, and passing them in the same manner. Before cutting" off
any of the half strands, the rope should be brought well upon a
stretch. Sometimes the whole strands are knotted, when divided,
and the half strands passed as above described. This splice does
not increase the diameter of the rope and is used for splicing a
fall or other rope that runs thru blocks or pulleys.
MECHANICAL MANEUVERS
USE OF KNOTS
Overhand Knot is used at the end of a rope to prevent un-
reaving or to prevent the end of a rope from slipping thru a block.
figure of Eight is used for purposes similar to the above.
Square or Reef Knot is used for joining two ropes of the same
size. With dry rope a reef knot is as strong as the rope ; with
wet rope it slips before the rope breaks, while a double sheet bend
or (Double Becket) is bound to hold.
Single Sheet Bend (Single Becket) is used for joining ropes
together, especially when unequal in size. It is more secure than
the Reef Knot but more difficult to untie. This is also known as
a Weaver's Knot.
Double Sheet Bend or (Double Becket) is used also for fasten-
ing ropes together of unequal size, especially wet ones, and is
more secure than the single sheet bend.
Two Half-Hitches is especially useful for belaying or making
fast the end of a rope around its own standing part. The end may
be lashed down, or seized, to the standing part with a bit of spun
yarn. This adds to its security and prevents slipping. This knot
should never be used for hoisting a spar.
Round Turn and Two Half-Hitches is like the preceding, except
that a turn is first taken around the spar or post.
Anchor Knot is used for fastening a rope to a ring or an anchor.
Clove Hitch, generally used for fastening a rope at right angles
to a spar, or at the commencement of a lashing. If the end of the
spar is free the hitch is made by first forming two loops, and plac-
ing the right-handed loop over the other one, then slipping the
loop over the end of the spar.
Timber Hitch, is used for hauling and lifting spars. It can
be easily loosed when the strain is taken off, but will not slip un-
der pull. When used for hauling spars, a half-hitch is added
near the end of the spar.
Telegraph Hitch, is used for hoisting or hauling a spar.
Hawser Bend, is used for joining two large cables. Each end
is seized to its own standing part.
Cat's Paw. It gives a double beai^ng surface, and will not cut
the rope.
Sheep Shank is used for shortening a rope, or to pass by a
weak spot, a half hitch is taken with the standing parts around
the Bights.
Mooring Knot. Take two turns round the moorings or snub-
bing post; pass the free end of the rope under the standing part;
MECHANICAL MANEUVERS
9
take a third turn above the other end and pass the free end be-
tween two upper turns.
Rolling Hitch, used for hauling a large rope or cable. Two
turns are taken around the large rope in the direction in which it
is to be hauled, and the one-half hitch made on the other side of
the hauling part. A most useful knot, and quickly made. For ar-
mored cable or wet manila rope, the hitch must be made with a
strap of rope yarn. Rope will not hold.
Blackwall Hitch, is used for attaching a single rope to a hook
of a block for hoisting. A variation is the Midshipman's Hitch;
the end is brought round the point of the hook, over the standing
part.
DIMENSIONS, WEIGHT, AND STRENGTH OF MANILA ROPE
(Taken from Eng. Field Manual)
Diameter
Circum-
ference
Weight in
pounds per
Breaking
Load.
Proper working
Load depending
100 feet.
upon age and
condition.
Inches
Inches
Pounds
Pounds
0.32
1
3.3
780
120-390
.48
m
7.4
1600
250-800
.64
2
13.2
2730
350-1300
.80
2^
20.6
4300
600-2000
.96
3
29.7
6100
900-2800
1.11
3^
40.4
8500
1100-4000
.27
4
52.8
11600
1500-5000
.43
4K
66.8
15000
2000-6500
.59
5
82.5
18400
2600-8000
.75
5^
99.8
22000
3000-10000
.91
6
119
25000
3500-11500
2.07
6^
139
29100
4000-13000
2.23
7
162
32700
4600-15000
2.39
iy>
186
36300
5000-1 6000
Up to 5 inches in circumference rope is made in coils of 1200
feet.
BLOCKS AND TACKLES
The parts of a Block are the Shell, or Frame, the Sheaves or
wheel upon which the rope runs, and the Pin upon which the
Sheaves turn in the shell ; and the sides of the shell are the Cheeks
and the Swallaw is the spare between the sheave and the frame
through which the rope passes. A Strap of iron or yoke is passed
around the Shell and forms attachments for a Hook atone end,
and an Eye at the other.
Blocks are made of Wood, Wood and Metal, and entirely of
Metal. In the latter case, the Strap is replaced by bolts at top
10 MECHANICAL MANEUVERS
and bottom, or the strap runs through the Eye of the Hook and
has a bolt securing the two ends at the bottom through a metal
grommet.
Blocks are designated by the Length of the Shell in Inches and
by the Number of Sheaves. The largest rope a wooden block will
take has a circumference equal to one-third the length of the
shell. Self-lubricating blocks may be obtained and are to be pre-
ferred. Blocks with one, two, three or four sheaves are called
Single, Double, Triple or Quadruple blocks.
A Snatch Block is a single block with a shell and strap open
at one side to admit a rope without passing the end through.
A Tail Block is a Single block, strapped with an Eye Splice,
and having a long end left by which to make the block fast to
any object.
Wooden blocks should be kept properly protected from weather
and damage from rough handling, well filled with paint and
properly lubricated.
Metal blocks should be painted, oiled and kept free from rust.
All blocks should be watched for cracked shells or sheaves and
worn pins.
TACKLES
A Tackle is a combination of ropes and blocks working to-
gether to aid in moving heavy weights. The moving block is the
running block, the fixed block is the standing block. From where
the end of the rope is made fast to one block to where it passes
over the first sheave in the other block, is called the Standing
Part, the rope between the blocks is the Running Part, and the
part to which the Pull is applied is called the Fall.
A Simple Tackle consists of one or more Blocks rove with a
single rope or fall. The end of the fall fixed in the Tackle is
called the Standing End; the other is the Running End.
To Over Haul is to separate the Blocks, to Round In to bring
them closer together. When the blocks are in contact they are
said to be Chockablock. •
By Power of a tackle is meant its mechanical advantage, or the
ratio of the force exerted by it to that applied to the Fall, or in
other words, it is the Weight Lifted divided by the Pull on the Fall.
The actual power of a Tackle may be obtained by first com-
puting the theoretical power.
The theoretical power of a tackle is obtained by assuming that
the rope is perfectly flexible, not elastic, and that the blocks have
no friction. It is (approximately) equal to the number of parts
MECHANICAL MANEUVERS 11
of the rope attached to or running from either side of the movable
block, or another simple rule is, the force applied multiplied by
the number of the moving parts equals the gaining power of the
tackle.
The above result is considerably modified in practice owing to
the loss of power due to friction of the sheaves and stiffness of the
rope. Under the supposition that the blocks are well lubricated
and that there is no twist in the tackle, the allowance to be made
for friction is 1/8 to 1/12 (an average of about 1/10) the weight
for each sheave in use, this of course depends on the kinds of
sheaves and the flexibility of the rope.
By means of the following formula the actual power of any
tackle may be calculated from the corresponding theoretical power :
p==W(m-fn)
mf
In which P = pull on the fall of the rope.
"W = weight to be raised.
f = theoretical power of the tackle.
n = number of sheaves.
— = the part of W to be added for each sheave in use.
m
The following example will illustrate the difference between
the actual power and the theoretical power of a tackle :
EXAMPLE 1. A Weight of 15,000 pounds is to be lifted by a
tackle consisting of two Treble blocks.
Required: (a) The theoretical pull required to lift the weight.
(b) The actual pull required to lift the weight.
SOLUTION: (a) Since there are six ropes leading to or away
from the movable block the theoretical power is 6.
The pull to be applied then =
. = 2500 pounds (Ans.)
6
W(m+n)
mf
W = 15000 pounds
m = 10
n= 6
f= 6
12
MECHANICAL MANEUVERS
__ 15000 X (10 + 6) 15000 X 16 _ 240000
60
10 X 6
60
4000 pounds (Ans.)
In solution (b) it requires 1500 pounds more pull to raise the
weight than it would have had there been no friction, as fric-
tion and stiffness of rope, represents a loss of about 60% in the
pull.
Whip (Figure 1). The simplest form of tackle; it is made by
a rope, rove through a single block.
Whip Upon Whip, so called where the block of one whip is
attached to the fall of another.
WHIP TACKLE
Figure 1
GUN TACKLE
Figure 2
LUFF TACKLE
Figure 3
Gun Tackle (Figure 2), is made by reeving a rope through two
single blocks and making the standing end fast to the upper block.
Luff Tackle (Figure 3) is made by reeving a rope through a
single and double block. Inverted it is called a Watch or Tail
tackle.
Luff Upon Luff. A luff tackle upon the fall of another luff
tackle is so called.
Gin Tackle consists usually of a double and a treble block, but
may consist of a single and a double block.
Single Burton, consists of two single blocks.
Double Burton, a single Burton with an additional whip at-
tached to its fall, the standing part of which is also attached to the
weight to be raised.
Spanish Burton, a gun tackle with a whip attached to its fall.
Double Spanish Burton, a luff tackle with a whip attached to its
fall in the same manner as a Spanish Burton.
When one tackle is applied to the Fall of another the power
MECHANICAL MANEUVERS
13
Figure 4
14
MECHANICAL MANEUVERS
obtained is found by multiplying their respective values together.
Example :— Luff upon Luff power equals 3 X 3 or power of 9.
LEVERS
There are three Classes, or orders, of levers, depending upon
the position of the fulcrum.
1st. (See Figure 5.)
Where the Fulcrum f is between the weight W and the point of
application of force P.
Figure 5
2nd. (See Figure 6.)
Where W is between f and P.
Figure 6
3rd. (See Figure 7.)
Where P is between f and W.
Figure 7
The distance from the point of application of the force to the
Fulcrum is called the Lever Arm L, and from the weight to the
Fulcrum the Counter Lever Arm Cl. This is on the supposition
that the Lever is straight and that W and P act at right angles to
it. Suppose now we have levers of the shape shown in Figures
MECHANICAL MANEUVERS
15
Figure 8
Figure 9
4J4J
Figure 10
47 1-4-
Figure 11
16
MECHANICAL MANEUVERS
8, 9, and 10, then L and Cl are the perpendicular distances from
f to the lines of application of P and W, where af is the counter
Lever Arm and bf the lever Arm.
Lever of the first class
Example: Use of handspike as a pry.
Lever of the second class
Example : Operating lever on hydraulic jack.
Example : The hoist arm on a crane or derrick.
In each of these classes the distance from the point of appli-
cation of the force to the fulcrum is called the lever arm (L) and
from the weight to the fulcrum the counter lever arm ( Cl ) .
Double Compound Lever — The mechanical advantage of this
T T '
lever is _ V _. in which L and L' Cl and Cl' pertain to the cor-
Cl Cl'
responding parts of the two levers. The power of a treble com-
T T ' T "
pound lever is _ v — X —
Cl Cl' Cl"
Figure 13
Figure 14
This variety of levers is exemplified in (a) the Windlass of a
(>nt, in which the Cl is the radius of the windlass and L the dis-
tance from the axis of the windlass to the point on the handspike
where the men take hold, when raising a weight.
(b) Capstan — where Cl is the radius of the drum and L is
the length of the capstan bars.
(c) Crab — this is a Compound Lever in which Cl and Cl' are
the radius of the smaller gear wheel, and L and L' the length of
the windlass arm and the radius of the larger gear wheel.
The mechanical advantage gained by a lever of any class may
be figured from the following:
MECHANICAL MANEUVERS
For Simple Lever _
Cl
L L'
For Compound Lever — X — -
V-<1 V^l
wxci wxci
Power to be applied = -- or P = --
L J-j
T vP T vP
Weight that can be lifted A, or W = ^— -
17
THE DIFFERENTIAL PULLEY
(See Figure 15.)
4J4?
Figure 15
This machine embodies the principles of the revolving lever,
combined with a single movable block.
Two pulleys of unequal diameters, having a common axle, are
rigidly attached to each other; an endless chain passes round the
larger pulley, A, down round the movable pulley, B, and up round
the smaller pulley; the upper pulleys are sprocket wheels, that is
they have projecting points or teeth in the rims into which the
18 MECHANICAL MANEUVERS
links of the chain fit to prevent its slipping when a weight is sup-
ported. The weight is suspended from the lower pulley, B, and the
force is applied to the chain at P.
The power of this tackle, neglecting friction, is :
/R-_r\
\ R /'
in which R = radius of large pulley, r = radius of small upper
pulley and the factor 2 enters, as each part, c and d, of the chain
evidently supports one-half the weight W.
EXAMPLE : — If the radius of the large pulley is 3 inches and
of the small pulley 2^ inches, the power of the tackle will be :
Q 3OT/W- 12, and if W = 600 Ibs., P = ^ = 50 Ibs.
O £l/2/
HYDRAULIC JACKS
Nomenclature. (See Figure 16.) There are two kinds of Dud-
geon 's Hydraulic Jacks ; namely, the Base Jack and the Horizontal
Jack. Both of these jacks are constructed according to the same
principle and the method of operation is the same for both. In
Coast Artillery, the horizontal jack only is used.
A Jack is a lifting machine. It is operated by means of a liquid
acting against a piston to raise it ; pressure on the liquid being
produced by means of a pump.
A force of a few pounds, from about 50 to not to exceed 150,
applied at the end of the pump handle or lever, produces a lifting
force of from 15 to 60 tons against the piston of the ram.
15, 20, 30, and 60 Ton Jacks are the sizes supplied by the Ord-
nance Department and these jacks may be used equally well in a
horizontal or upright position.
According to the principle of physics, (Law of Pascal), "When
a force or pressure is applied to a fluid contained in a vessel, this
force is transmitted equally in all directions throughout the fluid. ' '
Consequently if a force of 100 pounds be applied through a pipe
the area of whose cross section is one square inch, to a fluid in a
vessel, whose area is 100 square inches, the resultant force will
equal 100 times the original force, or 100 X 100 = 10,000 pounds.
This principle is made use of in the jack, for in its application to
the jack, the force is applied through a small pump channel to the
fluid contained in the ram cylinder. Assume the cylinder to be
about 30 times as great as the area of the channel, and that there
is 100 pounds of pressure transmitted through the opening of the
channel to the cylinder, then the piston (which just fits the cylin-
MECHANICAL MANEUVERS
19
20 MECHANICAL MANEUVERS
der) will receive an upward pressure or push of 30 X 100 = 3000
pounds. In other words, the original force of 100 pounds applied
through the channel to the fluid contained in the cylinder is
transmitted equally in all directions in the cylinder, and on each
area of the piston equal in size to the area of the channel is exerted
a force, (or push) equal to the original force (100 Ibs.)- As there
are thirty (30) such equal areas to the piston, and the fluid in the
cylinder is exerting the same pressure on each of these areas, it
is easy to see that the total pressure on the piston is thirty times
as great as the pressure through the channel where the area of
the opening of the channel is only one-thirtieth of the area of the
piston.
The Hydraulic Jack makes use of still another mechanical
principle. It is the lever. Examining the jack it is seen that the
pivot comes opposite the end of the lever. This is called the
Fulcrum of the lever. The weight (piston) is applied about one
inch from the piston end, or fulcrum. From the fulcrum to the
end of the handle of the lever where the force is applied is about
25 inches. This makes it a lever of the second class (the weight
between the fulcrum and the applied force), and gives a decided
mechanical advantage ; as the lever arm, or power arm (the distance
from the pivot or fulcrum to the point where the power is applied)
is twenty-five times as great as the counter lever arm, or weight
arm, which is the distance between the fulcrum and the point
of the lever when the weight is applied.
The Operation of the Jack.
1. The by-pass channel is closed by screwing down the lower-
ing valve, so that the only way the liquid can go is to the ram in
the cylinder.
2. The handle of the piston is placed in its socket, with the
projection downward.
3. Move the handle of the piston up and down, which pro-
duces the following results :
Motion from the lever is transmitted to the lever socket, -thence
to the knuckle which works up and down in a recess of the piston
and forces the piston up and down in the reservoir. The down
stroke of the piston closes the piston valve, and the pressure com-
presses the pump valve spring, opening the pump valve, thereby
forcing liquid through the channel to the ram cylinder. The
ram is forced up by pressure of the liquid in the cylinder against
the lower end of the ram as explained above. On the up stroke
of the pump piston, the pump valve spring forces the pump valve
up to the closed position and prevents the return of any fluid from
MECHANICAL MANEUVERS 21
the cylinder to the reservoir. This prevents the ram, supporting
the weight, from dropping down as the liquid is confined and prac-
tically non-compressible. On the up stroke of the piston the piston
valve drops down in the piston valve bonnet opening a passage
for the fluid which flows from the upper portion of the reservoir
through the two small holes in the piston and bonnet to replace
the fluid under the piston which the previous down stroke of the
piston has forced into the cylinder.
Instructions for Using.
1. Be sure the ram is down before filling.
2. Fill with one part alcohol (not wood alcohol) to one part
water with a teaspoonfull of sperm oil to prevent the water from
rusting the cylinder.
3. Care must be taken that no dirt gets into the reservoirs
in filling.
4. Fill reservoir to within an inch of the top and replace
the screw but do not screw up tight as an air passage is cut in it.
5. Never use water, kerosene, heavy oil, or glycerine to fill
the Jack. Water is liable to freeze and would rust the jack when
not in use. Kerosene destroys the packings and corrodes the metal
surfaces. Heavy oiis and glycerine soften the packing and gum
.and clog the valve parts.
6. Occasionally clean out the jack and refill it as the liquid
becomes thick and the jack will not work satisfactorily.
7. Always keep the ram down when not in use.
8. To raise the weight, screw the lowering valve tight on its
-seat and work the lever up and down.
9. To lower the weight, unscrew the lowering valve — two
turns are sufficient to lower as fast as required.
10. Use the claw or "S" hook when the jack cannot be placed
under the weight.
FIELD MANEUVERS
The implements and machines required for the various opera-
tions depend upon the kind and weight of the piece and the nature
of the maneuvers to be performed. For each exercise, those
specially required should be listed carefully and should be on the
ground before the work commences. When work is to be done,
due allowance must be made for the wear and tear, which, with
heavy materiel, is very considerable. Sound discretion should
be exercised not to allow the wearing to go beyond the limit of
safety.
22 MECHANICAL MANEUVERS
The machines and appliances usually employed for moving:
heavy artillery and other heavy objects are :
Ropes, Blocks and Tackles Derricks
Gins Shears
Hydraulic Jacks Blocks and Skids
Sling Carts Chocks
Hand Spikes Hand Carts
Railway Trucks Way Planks
Cradles Pinch Bars
Capstans Collars
Tractors Rollers
These are sufficient to manage the heaviest piece of Artillery
in the cases which ordinarily present themselves in service.
The Capstan is used as a strong purchase in heaving or hoist-
ing. When so employed, it is held in position by a stout chain
attached to hold-fasts. The rope is passed two or three times
around the barrel of the capstan, the free end coming off above
the turns ; the standing part is attached to the weight to be moved.
The rope is drawn taut by hand, the bars inserted in the mor-
tises, and the free end of the rope held and taken in by two men
seated on the ground.
Twelve men — three at each bar — are all that can be advan-
tageously employed. When additional power is required, the bars-
are swifted, that is, the ends of the bars are lashed together with
ropes, by which additional men take hold.
A Cradle is used to carry a gun when it is being moved on
rollers. It consists of two sections of Skids of suitable strength
and length, connected by two cross pieces which are joined and
bolted to the skids. The ends of the Skids are beveled off on the
bottom to permit engaging the rollers easily. The cross pieces are
hollowed out on top to receive the gun. The gun may be lashed
to the cradle if necessary. When making a turn, the front rollers
should be inclined in the direction of the turn and the rear rollers
in the opposite direction. The rollers may be knocked into place
with mauls. A body moving upon a roller gains twice the distance
passed over by the roller.
Blocks are rectangular prisms of wood employed extensively
in all operations connected with the movements of Heavy Artillery.
Skids are rectangular beams of wood used for similar purposes.
All Blocks and Skids should be sound, free from knots, and
perfectly true dimensions. When the edges become splintered
MECHANICAL MANEUVERS 23
and rounded by wear, they should be discarded, as with such
timbers it is impossible to erect safe and stable cribbing and sup-
ports. They should not be painted. The thickness of each should
be marked on both ends. In erecting a crib or other support, a level
foundation is of the first consideration, the Blocks should then be
laid crossing each other in alternate tiers, and the weights sup-
ported should be made to bear equally upon all sides of the base.
The Way Plank is an oak plank 15 feet long, 12 inches wide
and 3 inches thick. Each end is beveled for a distance of 6 inches,
the bevel on one end being on the side opposite the bevel of the
other end. These Planks are used chiefly for forming temporary
tramways for rollers, or for the wheels of carriage bearing heavy
weight.
The Pinch Bar is simply a stout handspike, or iron, with a
round-beveled butt, turned up into a blunt edge for the purpose
of catching under a gun or other similar object. It is used as a
lever, by pressing down, thus jumping the gun forward a very
short distance at a time. The butt end is of steel. The length of
the bar is from five to seven feet.
The Collar is a device placed upon the chase of a gun to make
its diameter equal to that of the body of the piece. This enables
the gun to be rolled with facility. It is made of pieces of scan-
tling joined together after the manner of the staves of a cask,
and hooped with stout bands of iron. It is shoved over the muz-
zle onto the chase, and secured with wedges of wood.
Chocks are made of solid oak wood, of various shapes and di-
mensions, those of triangular cross section being most common.
The grain of the wood runs lengthwise with the chock.
All implements and machines before being used, should be
most carefully examined in every detail, to see that they are ser-
viceable and suitable for the operation to be performed. None
should be put to uses for which they are not intended, nor sub-
jected to strains they are not constructed to bear.
It must be borne in mind that the giving away of one part
breaks and destroys other parts, frequently to an extent not readily
repaired, and, furthermore, endangers those working at the ma-
neuvers. Heavy weights must never be allowed to drop, even for
the shortest distances; they must be lowered to rest with a gentle
motion, and at the same time chocked to prevent rolling or sliding.
In hoisting, they must, when practicable, be closely followed up
with blocks or chocks to guard against any possible giving way.
All motions with heavy bodies must be slow, so as not to generate
momentum. Supports must have a firm base, and cribbing a level
24 MECHANICAL MANEUVERS
foundation, and be built up vertically. All holdfasts must be
secure beyond possibility of giving away.
Two or more men, lifting or hauling together, must wait for
the command before exerting their strength. The officer in charge
sees that all are ready before giving the command HEAVE.
Then all move with a prompt but steady effort, and apply their
power increasingly until the weight responds to their effort. The
command will be repeated as often as it may be necessary. When
the movement has been sufficiently made, the command EASE
AWAY is given. Those making the effort will then desist; but
at all times will be careful to avoid all sudden shocks or strains.
Every operation should be done with spirit and animation, but
without bustle or confusion. Vigilance should be constantly ex-
ercised to have the piece or rollers securely chocked.
When lifting a gun with Jacks, be sure and lift one end of the
gun at a time, the other being chocked on the cribbing.
A greased steel rail on top of a Skid will greatly facilitate
sliding a gun or slueing the trunnions.
The Handspikes used in mechanical maneuvers are beveled
on one side, as these will enter into places or under bodies where
square handspikes could not be used. When a handspike rests
on a fulcrum, and the weight on one end is to be raised by bearing
down on the other, the weight should never rest on the beveled
side, as the handspike would not then give a good hold, and would
be liable to split. In this case the beveled side should be down,
but if used for lifting, as when two handspikes are crossed under
the breech or chase of a gun to heave it upward, their ends resting
on the ground or platform, the beveled side should be up.
Parbuckling is the best method of rolling a gun. To do this,
place the gun on skids, and attach the rope by a bowline to one
of the trunnions, passing it under and around up over the gun,
and hauling on the end. If the gun is to be rolled up a slope, two
ropes of size suitable to the weight of the gun, are used. An end
of each rope is made fast to some fixed object at the upper part
of the slope; the other ends are carried under the chase and body
respective^, and up over the gun, these ends are hauled upon by
means of a capstan, or by attaching to them a fall and tackle.
The muzzle is slued forward when necessary, to compensate for the
greater distance traveled by the breech.
To Cross-Lift a piece or other object is to cross handspikes
under it from opposite sides. The butt end of the handspikes is
on the ground, and the power is applied by lifting at the other end.
MECHANICAL MANEUVERS 25
To Slue the Trunnions is to turn the piece on its axis so as to
bring the trunnions into any required position. This is done by
first placing the piece on skids perpendicularly to its axis. A
fulcrum is placed near the trunnion to be raised; upon this a
handspike or other lever is used, the piece meanwhile being chocked
on the opposite side, or a trunnion loop may be placed around the
trunnion to be raised, and a handspike or lever passed through it,
with the butt end resting on the top of the piece, the power applied
by lifting at the other end, the piece being chocked as before. Or,
by passing the bight of a rope once or twice around the piece and
placing the butt of a handspike or lever through the bight, and
bearing down or lifting up, using the piece as a fulcrum, the ends
of the rope being held to prevent them from slipping. All three
of these methods may be used at the same time. The skids should be
well greased under the piece, and likewise should be the chocks.
When the piece is of great weight, the hydraulic jack or gin is
advantageously used, provided, the axis of the trunnions are not
vertical. The former is placed under and the latter over the
trunnion to be raised. When the axis of the trunnions is vertical
or nearly so, a rope is passed around the gun and made fast to
one of the trunnions in a manner similar to the parbuckling ar-
rangement and hauled upon with tackle; meanwhile keeping the
gun from rolling with greased chocks. The chock may be kept in
place by passing a rope around its end, under the gun along each
slide of the skid and making fast around the end of the skid.
To Pinch a gun or other object is to move it by small heaves
with a pinch-bar or handspike, without allowing it to turn on its
axis. A piece is pinched one end at a time, the other being chocked.
The bar or handspike is placed as a lever, with the beveled side
down, and the power applied at the other end by bearing down.
To Launch a piece or other object forward or backward is to
move it in the direction of its axis. If the weight is such as to
require levers or handspikes, they are placed, usually, on opposite
sides, and the power applied by bearing down, at the same time
carrying the free end of the lever in a direction contrary to that
in which the object is to be moved.
To Slue a piece or other object, end for end, is to turn it around,
not allowing it to revolve on its longer axis.
The muzzle may be slued by pinching it along skids, or by
placing a roller or skid in the muzzle and hauling upon it with
tackle. Probably the best way of slueing the muzzle of a heavy
gun, is by means of a hydraulic jack and greased chock. Jack up
the muzzle until the inclined edge of the chock can be placed well
26 MECHANICAL MANEUVERS
under. Lower away on the jack, keeping the chock firmly in
place and allowing the muzzle to slide down its edge and onto
the skid. The jack will incline to one side and should be steadied
to keep it from falling.
To Cut is to move the object horizontally, without rolling, by
moving each end alternately in the required direction.
USE OF TRACTOR
OCCUPATION OF POSITION BY TACKLE
The occupation of position by tackle would only arise when it
was desired to keep the tractor on the road so as to avoid making
tracks which would destroy the concealment of the position or when
the position is so narrow that the tractor cannot go ahead of the
gun and put the latter in its position. With Wheeled Tractors,
this method is used not only to avoid making tracks, but also be-
cause frequently the soil is too soft and heavy to permit of the
tractor entering the position.
With any type of Tractor, this method necessitates the use of
a holdfast for the block of the tackle at the position. Holdfasts
may be available in the form of the walls of a standing or ruined
building, trees, etc. A tree should only be used if well grown and
sound. The strap should be placed as near the butt as possible
and still keep the ropes of the tackle off the ground. The excel-
lence of the following trees as holdfasts in general is in the order
named: Oak, Beech, Chestnut, Willow, Birch.
The best artificial holdfast is the Deadman. Dig a cross
trench at least five yards beyond the battery position, one yard
and a half long, twenty inches wide and one yard deep. At right
angles to its middle point dig an inclined trench to the bottom for
the strap of the tackle. Place a plank one yard and a half x 12" x
3" on edge at the bottom of the trench on the near side, then drive
in four stout stakes behind this plank. Now drop in a log or
timber about 12" in diameter, with the strap around it, behind
the four vertical stakes; drive four stakes obliquely into the rear
side of the trench, bearing on the log ; then drop into place between
the near wall and the vertical stakes another plank one yard and
a half x 12" x 3".
The kind of tackle to use generally depends more on the strength
of the rope than on the power of the tractor. In general, with
good rope, the luff tackle is sufficiently powerful. With extremely
soft ground or on a steep slope, depending on the kind of gun, the
four-foul tackle, two double blocks, or the five-fold tackle, a triple
MECHANICAL MANEUVERS 27
block and double block, may be required. Always err on the side
of choosing too powerful a tackle.
Safety Tackle. Whenever the gun has to be moved up or down
a very steep slope, a safety tackle of equal strength with the
maneuvering tackle should be reeved and attached to the gun and
made fast to a separate holdfast, The fall may be led to any
convenient and secure means of snubbing it. One or more men
should be detailed to handle this tackle. If the gun is being raised,
the safety tackle should be rounded in constantly to keep it taut,
the fall being snubbed the while. If the gun is being lowered, the
safety tackle should be paid out to keep pace with the movement
of the gun. Or the second tackle may be led to the pintle of another
tractor, and thus become a power tackle.
Use of Power Other Than the Tractor. The maneuver of guns
or other heavy vehicles may be accomplished by the use of tackle
according to the above principles with either horse-draft or man-
power on the fall. For the execution of difficult slow movements
horse-power is not satisfactory. With the size of rope ordinarily
furnished, not over forty men should be put on the fall of a tackle
in situations where the breaking of the rope would endanger the
gun. With the use of large cable, 200 men have been used effec-
tively on the fall of a tackle.
Crossing of Ditches. Ditches should be bridged by heavy
planks or filled with fascines.
Very Soft or Muddy Ground. Should be crossed by the use
of mats or by laying heavy planks crosswise for the wheels to run on.
USE OF TACKLE WITH THE HOLT TRACTOR
The Holt Tractor not being provided with a capstan, the fall
of the tackle is handled by making it fast to the tractor, which
then moves off the desired distance, the fall being cast off and
the tractor backing up when necessary for a new hold. A man
should be detailed to the fall, making fast to the tractor pintle
by a blackwall hitch and retaining the free end in his hand.
Another man should be detailed at the holdfast, to- keep the block
straight and the rope clear.
If it is desired to keep the tractor on the road it will generally
be necessary to change the direction of the fall by the use of a
snatch block on a second holdfast. For this holdfast it may be
convenient to use another Holt tractor, particularly if the change
of direction is not too abrupt.
Simultaneous Maneuvering of Guns. The time that the guns
are occupying or leaving a position is generally a most critical
28 MECHANICAL MANEUVERS
period for the safety of the Battery. Therefore every means
should be taken to shorten this period. Whenever the approach
to the position will permit the simultaneous maneuvering of the
guns, the work should be planned so that all guns may be put into
position by their own tractors simultaneously, even if it is nec-
essary to install a deadman for each gun. Sometimes it will happen
that one or more guns may be put in position by direct traction
while the others are being put in by tackle.
Use of One Holdfast for More Than One Gun. It will fre-
quently occur that a suitable natural holdfast is not on a line
through any one gun position at right angles to the battery front.
However, by starting each gun from a position on the road such
that a line from the gun to the holdfast will cross the gun position,
such a holdfast may be made to serve for two guns.
Use of Two Holdfasts for One Gun. On other occasions no
one natural holdfast will lead a gun to its position, but by leading
one or more parts of the tackle to another block at a holdfast
situated at a distance on the other side of the direct line to the
position from which the first holdfast is located, it will be possible
to haul the gun and direct it to its position. The influence on the
steering of the gun of the number of parts of the tackle led to each
holdfast must be considered.
Handling Artillery in Mountainous Country. This is a subject
which deserves special consideration. There are conditions of
Alpine warfare which require the emplacing of guns in almost
inaccessible places. To emplace the guns and also to maintain their
ammunition supply, resort has been had to aerial cableways and
other complicated and extensive use of cordage and tackle which is
outside the scope of the contemplated work of Tractor Artillery.
However, in order to fulfill its mission Tractor Artillery may need
to emplace its guns in very difficult positions. In order to meet
these conceivable situations, it is first of all necessary to accept as a
fundamental principle that given the necessary time and equip-
ment, any tractor weapon can be emplaced anywhere. The Prac-
tical applications of this principle by the limitations imposed by
the tactical situation upon the Time and Equipment to be used
in consideration of the object to be attained, ordinarily results in
the selection of very easily accessible positions for Tractor Artillery.
Negotiating a Bad Turn on a Mauntain Road. If the turn is so
sharp as to preclude the tractor or tractors making the curve with
the gun attached, it may be possible to uncouple the tractor, run
it round the turn, and then draw the gun around the turn with
tackles. For the first pull, it may be necessary to carry the rope
MECHANICAL MANEUVERS 29
from the gun through a snatch block at a holdfast on the upper
:side of the road. Then after the gun has completed part of the turn
the rope may be released from the snatch block for a direct pull.
If the turn is so abrupt that the gun alone cannot negotiate it,
there are still two recourses. 1st: the road may be widened. If
the soil is such as to make this difficult, haul the gun directly up
the slope from the lower reach of the road below the turn to the
upper reach above the turn. To do this, select three stout trees
above the upper road for holdfasts, or install deadmen. Rig
two heavy maneuvering tackles and one safety tackle. Run the
tractor or tractors hauling the gun around the curve and up out
of the way. Attach one maneuvering tackle to the limber, not to
the draw-bar, and ca-rry its fall through a snatch block at a hold-
fast on the lower road, back of the gun, to the tractor following.
Attach the second maneuvering tackle to the Gun Carriage proper,
leading its fall similarly through another snatchblock to a second
tractor on the lower road. Attach the safety tackle to the limber.
Using both maneuvering tackles, haul the gun up the slope, turning
and steering it by slings tied to the drawbar, leading to either side,
with the necessary number of men, 6 or 8, on each sling. After the
limber wheels surmount the edge of the upper road take most of
the strain on the tackle to the carriage itself, so as to facilitate
steering the gun into its position on the road. The fall of a tackle
should never be led directly to a tractor on the upper road, as the
sudden failure of a holdfast might drag the tractor off the road
before the tackle would yield to over hauling.
Emplacing a Gun in a Position With Steep Approaches. In gen-
eral it may be said that even if there is a road of suitable
gradient to the position, if this road is not amply wide with prac-
ticable curves, it is safer to handle the gun by tackle, by the
means indicated in the preceding paragraph. The important point
to observe is that the gun must be handled Straight Up the slope.
Only by this means can it be kept bearing on its wheels and avoid
overturning sidewise.
Lowering a Gun Down a Steep Slope. The three tackles
should be made fast to the gun carriage and the gun lowered,
limber first. The man steering the limber should use slings long
•enough so that they would not be caught by either the gun or
tackle in case of accident. Here again the important thing is to
avoid any tendency for the gun to overturn sidewise by keeping
it headed straight down the slope, thus providing equal bearing
for all the wheels. As an additional precaution, the falls after
"being led away from the tractor, should be snubbed around a
30 MECHANICAL MANEUVERS
tree, and an additional man detailed to keep the fall paying out
freely at the tree, but ready to snub it instantly when directed.
Rescuing Mired and Overturned Vehicles. If a motor vehicle
becomes mired, chains should be put on if not already on, and in
using its own power, the motor should not be accelerated exces-
sively. Opening the throttle wide generally serves merely to
spin the wheels, digging a deeper hole for the machine to drop
into. By using the clutch carefully, it is often possible to get
traction by short grips, without stalling the motor or digging deep
holes.
A vehicle which runs or slides partly off the road should always
back out rather than try to go ahead and steer up onto the road.
If there is another machine behind, it should give a tow, even if
only a light car. The towline should be made fast to the frame
rather than the front axle, and if possible, should be ten yards
long.
A vehicle which has overturned should first of all be unloaded
Then if the ground is soft and the vehicle is heavy, planks should
be placed under the lower wheels and the brakes set. If jacks;
are available, one should be used under either end as far up on the
body as the strength of the body will permit. Follow up the work
of the jack with blocking, improvised if necessary, and when
the jack has reached its limit, give it a new footing with blocking..
Before the vehicle raises high enough to right itself, secure it by a
guy rope so that it will not right itself with a crash, either snub-
bing the guy rope or using men on the fall. Or a shear may be
rigged. A light car or truck may be righted by the effort of the
number of men who can assemble around it. In any event, what-
ever means is used to lift the vehicle, all men available should bear
a hand, using improvised levers if possible.
THE GIN
A Gin is a tripod formed of three poles. Two of these poles:
called legs, are joined together by braces of wood or iron and
contained between them the Windlass. The third pole is called the
Prypole, and is joined to the Legs, at the top, by a bolt. This bolt
supports a Clevis to which the upper block of the tackle is hooked.
The Windlass is worked by two handspikes fitting into brass
sockets, one at each extremity of the windlass ; the operation of the
handspikes is made continuous by the action of a Pawl attached
to the socket on the Ratchet of the windlass.
The Prypole has cleats nailed to it to enable a man to mount to.
the head of the gin to hook on the block and to reeve the fall.
MECHANICAL MANEUVERS
31
To prevent the legs and prypole from sinking into the ground,
or injuring the pavement of casemates, stout pieces of wood,
called Shoes, are placed under them.
GARRISON GIN
The Hoisting apparatus consists of two blocks, through which
the fall is rove. The fall is wound two or more times around the
windlass.
There are three kinds of Gins used for Artillery purposes, the
Siege, the Garrison, and the Casemate.
The last two differ from each other only in height; the first
differs from the others in construction and size. Piper's Gin is an
improved modification of the Siege Gin.
GARRISON GIN
Figure 17. Garrison Gin
The Siege Gin (Old pattern) has no Clevis, as other gins,
instead of an upper block, two Sheaves are inserted between the
legs and secured by the bolt holding together the legs. The head
of the prypole is terminated by a flat piece of iron, which fits
between the heads of the legs above the sheaves and is secured by
another bolt.
This gin further differs from others in having three wooden
braces instead of two of iron. It has the disadvantage of being
exceedingly ill-contrived and unhandy.
The Garrison and Casemate Gins differ from the siege gin in
having two cross-bars, and in having the prypole inserted between
"32 MECHANICAL MANEUVERS
the legs, which are kept together by the Clevis Bolt. The upper
block (generally treble) is hooked to the clevis.
The casemate gin is made shorter than the garrison gin, so
that it may be hoisted in casemates.
When the gin is put together and raised, that part included
between the legs and the prypole is called the inside, the outside
being the part without the legs; the right corresponding to the
right hand of a man standing at the middle and outside of the
windlass, facing towards it.
The detachment is composed of 1 sergeant, 1 corporal, and 10
privates. The odd numbers are placed on the right and the even
numbers on the left side of the gin, all facing inwards. Nos. 1 and
2 opposite and one yard outside of the foot of the Prypole ; No. 9
outside of and near the foot of the right leg; No. 10, outside of
and near the foot of the left leg ; Nos. 3, 5, and 7 are between Nos.
1 and 9, dressing on them and dividing the intervening space into
equal distances; Nos. 4, 6, and 8, occupy similar positions with
respect to Nos. 2 and 10. In assembling the Gin the Corporal
-and Nos. 1 and 2 bring up the prypole ; Nos. 3, 5, and 7, the right
leg, and Nos. 4, 6, and 8 the left leg; Nos. 9 and 10 the windlass.
The Corporal superintends putting together the head, and the
Sergeant the placing of the windlass. The braces are brought up
•and adjusted to their places by Nos. 4, 6, 7, and 8.
All except the old pattern Siege Gin are put together and
hoisted by raising the head and bringing up the foot of the prypole
towards the foot of the legs.
The gin may be put together across the piece, or on the ground
near it, lying extended in the form of a T with the inside down.
The gin being together and lying on the ground, the Sergeant
commands RAISE THE GIN.
In raising it Nos. 9 and 10, each with a handspike, brace against
the lower cross-bar near the legs to prevent them from slipping;
Nos. 1 and 2 hold down the foot of the prypole, and at the same
time push up by the handle. The remaining numbers take hold to
lift by hand near the head.
The Corporal commands HEAVE, the head of the gin is raised
as high as the men can lift, and the prypole is pushed up; Nos. 3
and 4 go to the assistance of Nos. 1 and 2 at the handle of the
prj'pole; Nos. 5, 6, 7, and 8, lift the legs on their respective sides.
The command HEAVE is repeated until, by successive efforts,
the gin is raised. The prypole should be for the garrison gin,
about seventeen feet from the legs; for the casemate gin, about
thirteen feet.
MECHANICAL MANEUVERS 33
The gin is next placed over the piece by moving the legs and
prypole each a short distance at a time. To prevent them from
spreading too much, a lashing is passed from the prypole to the
legs or to the cross-bar.
To Reeve the Fall, fasten one end of a trace rope to the upper
block by passing it through the shell of the block. An expert man
ascends the prypole to the head, and passes the free end of the
rope through the clevis, from whence it is carried to the ground.
By heaving on the rope, the block is raised and the hook passed
through the clevis, with its point towards the prypole. The fall
is rove as explained for any tackle. The upper block may be
hooked to the clevis and raised with the gin; the fall may also
be rooved and the whole raised together. The extra weight thus
given makes the gin more difficult to lift.
The Corporal assisted by the most expert Privates, slings the
piece, and attends to all knotting and lashings.
In working the windlass, Nos. 1 and 2 hold on to the fall and
take up the slack; Nos. 7 and 9 work at the right, and Nos. 8 and
10 at the left handspike, Nos. 7 and 8 being next to the windlass.
To move the gin Nos. 1 and 2 station themselves at the handle
of the prypole; Nos. 9 and 10 each place a handspike under the
windlass from without, and near the legs; Nos. 7 and 8 assist to
lift these handspikes from within; at the command all move in
the direction indicated.
The gin is lowered in a similiar manner, but by inverse means
to that prescribed for raising it, by gradually drawing out the
prypole until the men can get near enough towards the head to
support it; it is then lowered upon the piece or on the ground; as
the case may be.
A gun may be moved horizontally with the gin by moving the
head of the gin two or three feet in the direction in which the
gun is to be moved. By hauling away on the windlass the gun
may be made to slide along the skids until it is directly under the
head of the gin. This operation may be repeated until the gun
is in the desired position.
The lifting capacity of the garrison gin is 17,000 pounds.
A Gin may be improvised by lashing three timbers together
arid erecting them in the form of a tripod. The lashing is made
as follows: Mark on each spar the distance from the butts to the
center of the lashing. Lay two of the spars parallel to each other
with an interval a little greater than the diameter. Rest their
tips on a skid and lay the third spar between them with its butt
in the opposite direction so that the marks on the three spars
34 MECHANICAL MANEUVERS
will be in line. Make a clove hitch on one of the outer spars
below the lashing and take eight or nine loose turns around the
three. Take a couple of frapping turns between each pair of
Spars in succession and finish with a clove hitch on the central
spar above the lashing. Pass a sling over the lashing and the
tripod is ready for raising.
SLING CART
The Sling Cart is used for moving guns or other heavy objects
short distances.
There are two kinds : The Garrison Sling Cart, for the heaviest
weights, is attached by its pole to a limber, or on the Hand Sling
Cart, and may be drawn by horses; the Hand Sling Cart is de-
signed for moving lighter wreights by hand.
With the hand sling cart the weight is raised sufficiently
from the ground to transport it by first attaching a sling of the
proper length to the weight to be moved and then raising the pole
uf the cart enough to permit the hook on the rear of the axle being
Jiocked into this sling. The pole in this case is used as a lever,
the axle and wheels form the fulcrum, and the weight is raised
by lowering the end of the pole. It may be used for transporting
any weight up to 6000 pounds.
, With the garrison sling cart the weight is raised by first
attaching to it a sling, and then applying to the sling the hooks
forming the lower part of a powerful screw passing up through
the axle of the cart. Above the axle is the nut of the screw, pro-
vided with long handles by means of which the screw is run up,
thus raising the weight.
The sling cart is capable of supporting 20,000 pounds.
SHEARS
Shears consist of two parts of suitable size for the weight to
be raised, lashed together in the form of an inverted F, suitably
guyed and inclined slightly from the vertical. They are generally
used for lifting heavy weights over the edge of a cliff or wharf,
in which case only rear guys are used. Weights may be moved
horizontally by manipulating the guys so as to change the inclina-
tion of the shears. They may readily be improvised from the
trunks of trees, etc., when no maneuvering materiel is on hand
except rope and tackle. A capstan is generally used in connec-
tion with shears, although a windlass may be improvised as ex-
plained later. All shears are constructed on the same principle.
The Spars when lashed in the form of shears are called the
Legs.
MECHANICAL MANEUVERS 35
The upper and lower ends of the spars are respectively called
the Head and the Heel, and the part where the lashing is applied
is called the Cross. Timbers placed under the heels to keep them
from sinking in the ground are called Shoes. The heels are kept
from slipping by Heel Lashings which are hitched to Heel Posts
on either side of the heels. Heel cleats which are spiked to the
.spars, keep the lashing from slipping up.
The Guys are usually fastened to the head by slings into which
one of the blocks of the guy tackle is hooked. When no guy
tackles are used, a bowline in the end of the guy serves the same
purpose. The upper block of the pain tackle is hooked into the
ends of a sling laid between the spars above the cross. A snatch
block hooked into a short sling laid around one of the spars under
the heel cleat, serves to change the direction of the fall when it
is run back to the capstan.
The stores necessary to equip a pair of shears are :
Guy Tackles — Two single blocks, two double blocks.
Main Tackle — One double block, one treble block, and one
snatch block.
Cordage — Main tackle fall, 100 fathoms 3 to 5 inch manila
.rope; guys, 50 fathoms 3 to 6 inch manila rope; head lashing,
10 fathoms 3 to 4 inch manila rope; heel lashing (two each), 10
fathoms 3 to 4 inch manila rope ; contingencies, 50 fathoms 3 to 4
inch manila rope.
Straps — Main tackle, one fathom 6-inch manila rope; snatch
block, one fathom 4-inch manila rope; holdfasts (six), each made
of one fathom 4-inch manila rope; Contingencies (six), each made
of a half fathom of 4-inch manila rope. Spun-yarn for mousing,
stops, etc., one ball of 100 fathoms.
Two Cleats for heels, to prevent the lashing from slipping
up, made by cutting lengthwise, diagonally, a piece of 6 by G
scantling 2 feet long. These cleats are spiked to the heels 6 inches
from the bottom. Twelve stakes for holdfasts for guys, 6 feet by
G inches; four stakes for heel posts; two shoes for heels, 6-irieh
plank, 1 foot by 4 feet.
To Rig the Shears, lay the ends of the spars on a trestle abou+
three feet high, the right leg above the left, so that they cross, at
about twice their thickness from the ends, with the heel in their
proper position.
Pass the head lashing as follows: Take a good piece of 3^
or 4 inch rope, well stretched, middle it, and make fast to the
shear leg, below the cross; with one pass the requisite number
of figure-of-eight turns around both spars, heaving each turn well
MECHANICAL MANEUVERS
taut, and hitch the end of the upper part of the shear leg; with
the other end pass riding turns around both legs, filling up the
intervals between the first turns, come up with the hitch of the
first end, and pass f rapping turns around all parts of the lashing
between the shears, finish with a square knot, and stop the ends
back with a good spun-yarn stop. If necessary tighten up with
wedges.
It may be done in another way as follows : The two spars for
the shears are laid alongside of each other with their butts on the
ground, the joints below where the lashing is to be, resting on
a skid. A clove hitch is made round one spar and the lashing
taken loosely eight or nine times about the two spars above the
hitch, without riding. A couple of frapping turns are then taken
between the spars and the lashing is finished off with a clove
hitch above the truns.
Figure 18. Shear Lashing
If Guy Straps are used, they can be put on doubled as follows :
Middle the strap, for the back guys, which should be about the
same size as that mentioned above and about 15 feet long when
doubled, having the splice at the side, so that it cannot enter into
either bight; lay the middle between the spars above the cross.
Each end is then led in opposite directions, around the spar
farthest away from the guy for which it is intended, and the ends
brought back around both spars crossed ready for the guy blocks
to be hooked into and moused. The strap for the fore guy is put
on, doubled in the same manner around the end of the spars, and
thus tMp strain of either and all guys tends to bind the spars
togetheil
If the straps are used singly, they can readily be put on by
raising the heels or butts and slipping them up the- spars, each
strap on that spar farthest away from the guy for which it is
intended, the straps crossing in the crotch and led to the blocks.
MECHANICAL MANEUVERS 37
If straps for the back and fore guys are not used, the back
guy is arranged as follows : The back guy, a good manila rope of
-3 to 6 inches, depending upon the weight to be raised, and of con-
venient length to 50 fathoms, is middle, and the middle placed
above the cross, the left-hand end leading downward, bring the
left-hand end up around the end of the right leg, then between
the legs and around the head of the left leg, and carry it over
to the left side of both legs ; carry the right-hand end around the
left leg, under the right leg, up the left side of both legs and across
the left-hand end, seize the crossing with spun-yarn, the ends
of the guys leading to the blocks opposite the sides of the cross
from which they come.
In the case of a single back-guy, particular care must be taken
to bring the axis of the shears in the vertical plane containing the
holdfast and the center of gravity of the weight to be lifted.
The Main Tackle Strap or Sling, when these back and fore
guys are used, is put on over the cross, passing over the whole of
the straps, except the bights of the back and fohre guy straps.
The main tackle strap is put on as follows: Place the middle
of the strap doubled, which for the heavier purposes is a six inch
Manila rope of sufficient length, under the cross above the fore
bring the ends up over the cross above the fore guy, then down
underneath; hook the upper block to them under the cross below
the fore guy and mouse the hook, taking care that the splice or knot
does not come in the middle of the strap and that the fall leads to
the rear. Or the main tackle strap, if used singly, can be put on
by raising the heel or butt and slipping it up one of the spars,
and putting it in the cross over the head lashings and other straps ;
its bight, \\hich should be fitted with a thimble, should hang low
enough to enable the upper block of the main tackle to swing
clear between the spars when raised. Should it be required to
shorten it, one or more turns are taken with the strap around
the head of the spars.
Two cleats are spiked to the heels, 6 inches from the ends. Lay
the shoes under the heels. The shoes should be on the same level,
and in bad ground, prevented from sinking or slipping by placing
planks, brush-wood or other materiel underneath, securing them
by pickets. Drive the heel posts or stakes, two for the lighter
weights, one on each side of each leg, about a foot toward the
head, and one foot outside; make a timber hitch around the inner
posts with the heel lashings, pass three turns around the leg below
the cleats, and hitch the lashings to the outer posts. For the
heavier weights four pickets should be driven for each heel, one
38 MECHANICAL MANEUVERS
at each angle and outside of the shoes, a clove hitch is made with
the center of the ropes around each foot below the cleats, arid the
ends led to opposite holdfasts. As many turns are taken
around the heel posts as may be necessary, the running ends being
brought below to prevent their jamming as the shears rise.
Drive four holdfasts for each back-guide as fallows: Two on
each side, three feet apart in a line of the legs prolonged, at a
distance from the heels twice the length of the spars from the
heels to the crotch, and two more stakes six feet in rear of these.
Lay the bight of a strap for holdfasts over the front stake;
connect each pair of front and rear stakes with a strap twisted
up taut to insure the strain being distributed over all the stakes;
drive two stakes for holdfasts for the first guy, one in rear of the
other, in the prolongation of the axis of the shears at a distance
from the heel twice the length of the spars from the heels to the
crutch. The length of the guys should >be about four times this
distance.
Hook the upper block in the end guy tackle to the bight of the
strap, and the other block to the holdfast strap, which is over
the front stakes; mouse all hooks. If stakes are not driven for
holdfasts, any convenient hold can be taken around a tree, gun
or pintle.
Ordinarily the fore guy can be worked without a tackle, belay-
ing it over the holdfasts, first taking a round turn over the one
next the shears.
If not too heavy, the shears may be raised by lifting the head
and hauling on the guy tackles, slacking the heel lashings as
required, and tending the fore guy carefully to prevent the shears
falling over toward the rear.
When raised, hook the snatch block to a strap placed below the
cleat on the leg on that side from which the fall leads,
placing the block as low as possible, so that the fall will lead hori-
zontally to the drum of the capstan.
If the shears are too heavy to raise in this way, bring both
guys together at the heels; form a crutch by lashing together two
poles (or use the legs of the garrison gin) ; place the guys in this
crutch; pass the end of a small rope over both guys, in front of
the crutch, down under the lashing, and take a rolling hitch with
it around one of the guys in rear of the crutch ; haul the rope well
taut, and secure it to the lower end of the crutch leg.
Raise the crutch with an inclination of one-sixth to the front,
and heave up the shears by the guy tackles. When the crutch
ceases to act, slack it to the ground by the small rope.
MECHANICAL MANEUVERS 39
In general the inclination or rather rake of the shears should
not exceed twenty (20) degrees, or four-elevenths of their height,
and each leg should have about one-half of this inclination. In
this position the strain on the guys will never exceed one-half
the weight.
The shears are lowered by slacking the guys and heel ropes,
or by small shears or lever.
The following diagram will serve as a guide in placing shears,
holdfasts, etc. :
Figure 19
AD and BC are the legs of the shears.
F, the front guy holdfast.
G, the rear holdfast.
E, the center of the line AB, at right angles to FG.
AD = BC
The splay ,AB = 1/3 CE.
FF and EG = at least 2 AC.
The lashing to be twice the thickness of the spars from the
ends. When two fore or two rear guys are used, the holdfasts
should lie in prolongation of the legs, at a distance equal to EG
and EF.
When the locality will not admit of rigging the shears in
position as described, they may be raised from the foot of the
wall or cliff by means of a gin or lighter shears in the following
manner: Pass the shear lashing and attach the front guy; lash a
stout spar across the legs about two feet above the center of
gravity, giving the heels the proper -spread; fasten a small rope
to each heel to serve as guys ; hook the gun tackle to a strap firmly
attached to the middle of the cross-spar, and heave away, tending
the guys carefully. As the head of the shears comes above the
crest of the wall, put on the back guys and main-tackle strap
and hook on the tackle; mouse all hooks; raise the shears, place
the heels on the shoes, pass the heel lashings, set up the guys, and
lower the gin to the ground, leaving the spar in position.
When no capstan is availible, a windlass may be improvised
as follows : Nail a strong cleat on the upper side of each leg and
about two feet from the heel, the butt, or square end of the cleat
40 MECHANICAL MANEUVERS
down; lay a round spar a little more than one-third the length of
the shears across the legs, one foot above the butt of the cleats;
pass loosely two strong lashings (3-inch rope) around this spar
near the ends or near where it rests on the legs ; f rap the lashings
near the spars) and tie the ends. The lashing should be loose
enough after frapping to leave loops to pass over and under the
butts of the cleats, taking care to have them of equal length. Grease
the spar and legs where they are in contact, and the spar under
the lashing. Pass two or more straps of \.l/2 or 2 inch rope doubled
around the end and middle of the spar, put one end through the
bight of the other and take a turn around the spar. Put a hand-
spike the free bight . to be used as a lever to turn the windlass.
These straps should be nailed to the spar to prevent slipping.
The windlass is chocked by allowing two or more handspikes
to touch the ground on the opposite side of the windlass.
Light guns may be passed over ditches or from different places
practically at the same level, but too far apart for one pair of
shears to be used, by means of two pairs of shears as follows :
Big two shears as described above, one on either side of the
ditch, except that the back guy is necessary for each.
The shears, when raised, should be nearly vertical, only inclined
slightly toward each other, for the strain is sometimes excessive
on the guys.
Before raising the shears, connect the heads by a gun tackle
purchase, the fall which is slacked off as the shears rise, leading
to either side as desired.
The back guys, and the two main tackles for the gun or weights
mentioned, should be luff-tackle purchases.
Straps or suitably sized ropes should be used and adjusted
over the heads of the shears, as described before for the back guys
and for the gun tackle purchase for connecting the shear heads.
After the shears are raised and guys well secured, both main
tackles are hooked into straps, passed around the gun and
trunnions, and the hooks moused.
The gun is passed across by hauling on one tackle and at the
same time slacking off the other.
Both falls can be led to the same side of the ditch, if desired,
but to different capstans.
When the garrison or casemate gin is used as shears the
prypole is replaced by a parting block of the same diameter.
The guys are attached as follows : Middle the rope for the back
guys; push the bight through the clevis from below and slip it
around both legs ; haul the ends back tight and lay them over the
MECHANICAL MANEUVERS 41
head of the gin to the rear, each part lying bet\v*een the nearest
leg and the parting block, taking care to place canvas under the
ropes to prevent chaffing.
The fore guy is hitched around the clevis belt.
A single back guy may be used, formed of a tackle of the same
size as the gin tackle, hooked into a strap applied as described
for the guy ropes. In this case particular care must be taken to
bring the axis of the shears in the vertical plane containing the
holdfast and the center of gravity of the weight to be lifted.
A Gin Pole is a single spar raised and operated in the same
manner as shears. It is generally fitted with four guys, the
fore guys extending at an angle of 45° from the line of the front,
the rear guys at an angle of 45° from the line of the rear. A cleat
is spiked to each side of the spar near the head to keep the guy
straps and main tackle sling from slipping down. A turn or two
is taken around the spar with the guy straps doubled, letting the
ends come clear to allow a guy tackle block to be hooked into each.
The main tackle sling is put on in the same way, the upper block
being hooked into both ends. A heel cleat is spiked to each side
of the spar and the heel lashings, heel posts, and shoes are used
as for the shears.
Approximate Size and Length of Spars Required for Shears.
Weight to be raised Mean Diameter Length
2 tons 7 to 9 inches 20—30 feet
3 to 5 tons 11 to 13 inches 30 — 40 feet
5 to 12 tons 13 to 16 inches 40—50 feet
12 to 25 tons 16 to 24 inches 50—60 feet
For a gin pole a spar approximately 1/3 great mean diameter
than given above should be used.
HOLDFASTS
To prepare a fastening in the ground for the attachment of
guys or purchases, stout pickets are driven into the ground, one
behind the other in line of pull. The head of each picket except
the last is secured" by a lashing to the foot of the picket next
behind. The lashings are tightened by rack sticks, the points
of which are driven into the ground to hold them in position.
The distance between the stakes should be several times the height
of the stake above the ground.
Another form requiring more labor but having much greater
strength is called a Deadman, and consists of a log laid in a
transverse trench with an inclined trench intersecting it at its
42 MECHANICAL MANEUVERS
middle point. The rope is passed down the inclined trench, takes
several turns around the log and is fastened to it by half hitches
and marline stoppings. If the cable is to lead horizontally or
inclined downward it should pass over a log at the outlet of the
inclined trench. If the cable is to lead upward this is not neces-
sary, but the anchor log must be buried deeper.
TO »t.
Y.
m.m 21,1908
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